BUG: VTS_UI1 and VTS_PUI1 are Defined Incorrectly in AfxDisp.h

• The Microsoft Foundation Classes (MFC), included with:
  • Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1, 4.2, 5.0, 6.0

SYMPTOMS

When using the string literals defined for VTS_UI1 or VTS_PUI1 in calling COleDispatchDriver::InvokeHelper() or CWnd::InvokeHelper(), you might get strange results. You might notice any of the following symptoms when using the values defined in AfxDisp.h:

• An ASSERT on line 321 in file Oledisp2.cpp in the COleDispatchDriver::InvokeHelperV function.



• A message box stating "Bad variable type."



• An uncaught exception in WindowProc.



• A first chance exception in Kernel32.dll.

CAUSE

This is because VTS_UI1 and VTS_PUI1 are defined incorrectly in the Afxdisp.h header file.

RESOLUTION

Do not use VTS_UI1 or VTS_PUI1 in any of your code. Instead, define the correct values for each of these using a name you assign. Code like the following can be used:

//Do NOT use VTS_UI1. It has a value of "0x0F" which is incorrect.
//The correct value for VTS_UI1 is 17 or 0x11
#define MY_VTS_UI1 "\x11"

//Do NOT use VTS_PUI1. It has a value of "0x4F" which is incorrect.
//The correct value for VTS_PUI1 is 81 or 0x51
#define MY_VTS_PUI1 "\x51"

void SomeFunction(BYTE byteVal)
{
 static BYTE parms[] = MY_VTS_UI1; // please note that this is not VTS_UI1
 DISPID dispid = 0x60030000;       // notice that this is different!

 COleDispatchDriver d;
 if (d.CreateDispatch("SomeComObject.SomeComObject.1))
    d.InvokeHelper(dispid, DISPATCH_METHOD, VT_EMPTY, NULL, parms, byteVal);
} 

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

REFERENCES

Q241862 BUG: ClassWizard Omits Methods that Take BYTE or BYTE* as Parameters

Additional query words: 0x80020008 COleException InvokeHelper Invoke IDispatch OLE Automation

Keywords : kbAutomation kbCOMt kbMFC kbVC400bug kbVC410 kbVC420 kbVC500bug kbVC600bug kbDSupport kbGrpMFCATL
Version : winnt:4.0,4.1,4.2,5.0,6.0
Platform : winnt
Issue type : kbbug